Emits chunks at a roughly constant data rate. Chunks are in a very particular
format: the output data is verifiable, but sufficiently non-deterministic
that two different instances of this adaptor are very likely to have
distinct outputs.
Each chunk is full of random bytes; the randomness comes from
an instance of java.util.Random seeded with the offset xored
with the time-of-generation. The time of generation is stored, big-endian,
in the first eight bytes of each chunk.